CPU is made up of tiny transistors in millions of quantity, so this micron process rechnology is used to determine the quantiy of transistors on CPU Die (the tiny Embossed portion of the CPU).

so lesser microns it has, more transistors it can support, for example, if the CPU die (that embossed porion) is 66 millimeter Square/Rectcangle, then on say 18 micron Die structure, it might can suport 38 Million transistor , on 13 micron it acn suport say 48 million, and on 9 micron it can support 58+ million (this figure with 9 micron and 58 million is correct, others are assumed to give u example) .